Method for dynamic stabilization of PET detector gains
Inactive Publication Date: 2005-02-22
GE MEDICAL SYST GLOBAL TECH CO LLC
View PDF10 Cites 13 Cited by
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Benefits of technology
In an alternative embodiment, a method for improving image performance in PET imaging by stabilizing gain in compensators which are separately adjustable so that received digital signals are adjusted to compensate for PMT degradation, includes calculating PMT signal adjustments within a calibrator and adjusting output of compensators with the PMT signal adjustments, wherein the steps of calculating and adjusting are repeated during image acquisition in a PET scanner system until a number of photons absorbed by a corresponding crystal does not exceed a count threshold.
Problems solved by technology
While operation of a PET detector is relatively simple in theory, unfortunately, despite efforts to manufacture components that operate in an ideal fashion, there is an appreciable variation in how similar detector components respond to identical stimuli.
In this case detection circuitry may erroneously identify a third crystal between the first and second crystals as the detecting or absorbing crystal.
In addition to the potential errors described above, other sources of system error also occur.
Exacerbating matters, over time PMT performance has been known to degrade due to aging related changes in structure.
For instance, PMT output signals have been known to vary as a function of temperature, ambient magnetic fields and other parameters that are relatively difficult or expensive to control.
While calibration techniques like the one described above are useful, unfortunately, most calibration techniques require acquisition of massive amounts of data and hence an appreciable amount of time to complete.
In addition, in cases where calibration is only performed when a radiologist begins to recognize artifacts, the radiologist is routinely faced with the question of whether or not to recalibrate.
Method used
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View moreImage
Smart Image Click on the blue labels to locate them in the text.
Smart ImageViewing Examples
Examples
Experimental program
Comparison scheme
Effect test
Embodiment Construction
While various components are described below for carrying out several inventive methods, it should be appreciated that all of the methods herein may be performed by any of several different commercially available and programmable processors.
Referring now to the drawings, wherein like reference characters and symbols represent corresponding elements and signals throughout the several views, and more specifically referring to FIG. 1, the present invention will be described in the context of an exemplary PET scanner system 8. System 8 includes an acquisition system 10, an operator work station 15, acquisition, locator and coincidence (ALC) circuitry 30 and an image reconstruction processor 40.
System 10 includes a gantry 9 which supports a detector ring assembly 11 about a central bore which defines an imaging area 12. A patient table (not illustrated) is positioned in front of gantry 9 and is aligned with imaging area 12. A patient table controller (not shown) moves a table bed (not sh...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More PUM
Login to View More Abstract
A method and apparatus for calibrating PET PMTs includes conducting a calibration procedure and determining whether a number of photons absorbed by a corresponding crystal exceeds a count threshold. If the threshold is exceeded the steps of conducting a calibration procedure and determining whether a number of photons absorbed by a corresponding crystal exceeds a count threshold would be repeated and if the threshold is not exceeded then the calibration procedure would be ended.
Description
BACKGROUND OF THE INVENTIONThe present invention relates to PET scanners generally and specifically to a method and apparatus for adjusting PMT gains to compensate for drift due to various operating phenomenon.Positrons are positively charged electrons which are emitted by radionuclides which have been prepared using a cyclotron or other device. The radionuclides most often employed in diagnostic imaging are fluorine-18, carbon-11, nitrogen-13 and oxygen-15. Radionuclides are employed as radioactive tracers called “radiopharmaceuticals” by incorporating them into substances such as glucose or carbon dioxide. One common use for radiopharmaceuticals is in the medical imaging field.To use a radiopharmaceutical in imaging, the radiopharmaceutical is injected into a patient and accumulates in an organ, vessel or the like, which is to be imaged. It is known that specific radiopharmaceuticals become concentrated within certain organs or, in the case of a vessel, that specific radiopharmece...
Claims
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More Application Information
Patent Timeline
Login to View More IPC IPC(8): G01T1/164G01T1/00G01T1/29
CPCG01T1/2985A61B6/037
InventorWILLIAMS, JOHN JAYSTONGER, KELLY ALAN
OwnerGE MEDICAL SYST GLOBAL TECH CO LLC